This invention relates to a process for the partial oxidation of high metals or ash containing liquid hydrocarbonaceous or a slurry of solid carbonaceous fuel to produce synthesis gas, reducing gas or fuel gas.
When gasifying heavy oil, coke or other feedstock with a high metals or ash content in admixture with recycle feed, the ash in the fresh feed may be increased by the addition of any ash that may be contained in the recycle fuel feed. In some cases, the higher ash content of the total feed (fresh plus recycle) may cause fouling of the waste heat recovery system located just downstream from the gasifier. This fouling tendency may be reduced by splitting part of the flow to a quench section such as described in coassigned U.S. Pat. Nos. 3,998,609 and 4,411,670, which are incorporated herein by reference. By the subject invention, the tendency for fouling of waste heat recovery equipment is reduced still further, and the net unconverted carbon produced may be also reduced without lowering the cold gas efficiency. The cold gas efficiency is the ratio of the higher heating value of the product gas times 100 divided by the higher heating value of the fuel fed to the gas generator. Ordinarily, there is a drop in cold gas efficiency above a certain level of atomic O/C ratio and conversion. This level is raised by the subject invention so that the net unconverted carbon produced may be reduced without lowering the cold gas efficiency.
Coassigned U.S. Pat. Nos. 3,232,728 and 3,639,261 relate to quenching and scrubbing of raw synthesis gas with water or oil to produce clean gas. Soot recovery and recycle to the gas generator as a portion of the feed is described in coassigned U.S. Pat. Nos. 2,999,741; 3,044,179 and 4,134,740. These coassigned U.S. patents are incorporated herein by reference. In U.S. Pat. Nos. 4,060,397 and 4,407,206 all of the gaseous effluent from one combustion zone is further reacted in a second zone. In comparison with the subject invention, the processes in these two patents provide no simultaneous production of two split streams of gas, one stream saturated and the other unsaturated. Further, unlike the subject invention, they provide no cleaning of the product gas to produce a slurry of particulate carbon, soot and ash which is fed through a burner and reacted by partial oxidation in a reducing atmosphere that includes one of the split streams of gas.